Solve for $z$ : $-24 = -28 + z$
Solution: Add $28$ to both sides: $ \begin{eqnarray} \\ \hphantom{-24 {+ 28}} &\hphantom{=}& \hphantom{z} \\ -24 &=& -28 + z \\ \\ {+28} && {+28} \\ \end{eqnarray} $ $ \begin{eqnarray} \\ -24 {+ 28} &=& z \\ \end{eqnarray} $ Simplify. $ z = 4$